1 import jdk.incubator.code.*;
 2 import jdk.incubator.code.Reflect;
 3 import jdk.incubator.code.analysis.SSA;
 4 import jdk.incubator.code.interpreter.Interpreter;
 5 import org.junit.jupiter.api.Assertions;
 6 import org.junit.jupiter.api.Test;
 7 
 8 import java.lang.invoke.MethodHandles;
 9 import java.lang.reflect.Method;
10 import java.util.Optional;
11 import java.util.function.Predicate;
12 import java.util.stream.Stream;
13 
14 import static jdk.incubator.code.dialect.core.CoreOp.FuncOp;
15 import static jdk.incubator.code.dialect.core.CoreOp.VarAccessOp.VarLoadOp;
16 import static jdk.incubator.code.dialect.core.CoreOp.VarAccessOp.VarStoreOp;
17 import static jdk.incubator.code.dialect.core.CoreOp.VarOp;
18 
19 /*
20  * @test
21  * @modules jdk.incubator.code
22  * @run junit TestRemoveFinalVars
23  */
24 
25 public class TestRemoveFinalVars {
26 
27     @Reflect
28     static boolean f() {
29         final int x = 8; // final var
30         int y = x + 2; // final var
31         int z = y + 3; // non final var
32         z++;
33         return x == 8 && y == 10 && z == 14;
34     }
35 
36     @Test
37     void test() {
38         FuncOp f = getFuncOp(this.getClass(),"f");
39         System.out.println(f.toText());
40         FuncOp lf = lower(f);
41         System.out.println(lf.toText());
42 
43         FuncOp f2 = f.transform(TestRemoveFinalVars::rmFinalVars);
44         System.out.println(f2.toText());
45         FuncOp lf2 = lower(f2);
46         System.out.println(lf2.toText());
47 
48         Assertions.assertEquals(Interpreter.invoke(MethodHandles.lookup(), lf2), Interpreter.invoke(MethodHandles.lookup(), lf));
49 
50         Op op = SSA.transform(lower(f));
51         System.out.println(op.toText());
52     }
53 
54     static FuncOp lower(FuncOp funcOp) {
55         return funcOp.transform(CodeTransformer.LOWERING_TRANSFORMER);
56     }
57 
58     static Block.Builder rmFinalVars(Block.Builder block, Op op) {
59         if (op instanceof VarOp varOp) {
60             // Is the variable stored to? If not we can remove it
61             // otherwise, it's not considered final and we copy it
62             if (isValueUsedWithOp(varOp.result(), o -> o instanceof VarStoreOp)) {
63                 block.op(varOp);
64             }
65         } else if (op instanceof VarLoadOp varLoadOp) {
66             // If the variable is not stored to
67             if (!isValueUsedWithOp(varLoadOp.varOp().result(), o -> o instanceof VarStoreOp)) {
68                 // Map result of load from variable to the value that initialized the variable
69                 // Subsequently encountered input operations using the result will be copied
70                 // to output operations using the mapped value
71                 CodeContext cc = block.context();
72                 cc.mapValue(varLoadOp.result(), cc.getValue(varLoadOp.varOp().operands().get(0)));
73             } else {
74                 block.op(varLoadOp);
75             }
76         } else {
77             block.op(op);
78         }
79         return block;
80     }
81 
82     private static boolean isValueUsedWithOp(Value value, Predicate<Op> opPredicate) {
83         for (Op.Result user : value.uses()) {
84             if (opPredicate.test(user.op())) {
85                 return true;
86             }
87         }
88         return false;
89     }
90 
91     static FuncOp getFuncOp(Class<?> c, String name) {
92         Optional<Method> om = Stream.of(c.getDeclaredMethods())
93                 .filter(m -> m.getName().equals(name))
94                 .findFirst();
95 
96         Method m = om.get();
97         return Op.ofMethod(m).get();
98     }
99 }